Archaeoastronomy

Archaeoastronomy (also spelled archeoastronomy) is the interdisciplinary or multidisciplinary study of how people in the past "have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultures". Clive Ruggles argues it is misleading to consider archaeoastronomy to be the study of ancient astronomy, as modern astronomy is a scientific discipline, while archaeoastronomy considers symbolically rich cultural interpretations of phenomena in the sky by other cultures. It is often twinned with ethnoastronomy, the anthropological study of skywatching in contemporary societies. Archaeoastronomy is also closely associated with historical astronomy, the use of historical records of heavenly events to answer astronomical problems and the history of astronomy, which uses written records to evaluate past astronomical practice.

Archaeoastronomy uses a variety of methods to uncover evidence of past practices including archaeology, anthropology, astronomy, statistics and probability, and history. Because these methods are diverse and use data from such different sources, integrating them into a coherent argument has been a long-term difficulty for archaeoastronomers. Archaeoastronomy fills complementary niches in landscape archaeology and cognitive archaeology. Material evidence and its connection to the sky can reveal how a wider landscape can be integrated into beliefs about the cycles of nature, such as Mayan astronomy and its relationship with agriculture. Other examples which have brought together ideas of cognition and landscape include studies of the cosmic order embedded in the roads of settlements.

Archaeoastronomy can be applied to all cultures and all time periods. The meanings of the sky vary from culture to culture; nevertheless there are scientific methods which can be applied across cultures when examining ancient beliefs. It is perhaps the need to balance the social and scientific aspects of archaeoastronomy which led Clive Ruggles to describe it as "a field with academic work of high quality at one end but uncontrolled speculation bordering on lunacy at the other".

In his short history of 'Astro-archaeology' John Michell argued that the status of research into ancient astronomy had improved over the past two centuries, going 'from lunacy to heresy to interesting notion and finally to the gates of orthodoxy.' Nearly two decades later, we can still ask the question: Is archaeoastronomy still waiting at the gates of orthodoxy or has it gotten inside the gates?

— Todd Bostwick quoting John Michell

Two hundred years before John Michell wrote the above, there were no archaeoastronomers and there were no professional archaeologists, but there were astronomers and antiquarians. Some of their works are considered precursors of archaeoastronomy; antiquarians interpreted the astronomical orientation of the ruins that dotted the English countryside as William Stukeley did of Stonehenge in 1740, while John Aubrey in 1678 and Henry Chauncy in 1700 sought similar astronomical principles underlying the orientation of churches. Late in the nineteenth century astronomers such as Richard Proctor and Charles Piazzi Smyth investigated the astronomical orientations of the pyramids.

The term archaeoastronomy was advanced by Elizabeth Chesley Baity (following the suggestion of Euan MacKie) in 1973, but as a topic of study it may be much older, depending on how archaeoastronomy is defined. Clive Ruggles says that Heinrich Nissen, working in the mid-nineteenth century was arguably the first archaeoastronomer. Rolf Sinclair says that Norman Lockyer, working in the late 19th and early 20th centuries, could be called the 'father of archaeoastronomy'. Euan MacKie would place the origin even later, stating: "...the genesis and modern flowering of archaeoastronomy must surely lie in the work of Alexander Thom in Britain between the 1930s and the 1970s".

In the 1960s the work of the engineer Alexander Thom and that of the astronomer Gerald Hawkins, who proposed that Stonehenge was a Neolithic computer, inspired new interest in the astronomical features of ancient sites. The claims of Hawkins were largely dismissed, but this was not the case for Alexander Thom's work, whose survey results of megalithic sites hypothesized widespread practice of accurate astronomy in the British Isles. Euan MacKie, recognizing that Thom's theories needed to be tested, excavated at the Kintraw standing stone site in Argyllshire in 1970 and 1971 to check whether the latter's prediction of an observation platform on the hill slope above the stone was correct. There was an artificial platform there and this apparent verification of Thom's long alignment hypothesis (Kintraw was diagnosed as an accurate winter solstice site) led him to check Thom's geometrical theories at the Cultoon stone circle in Islay, also with a positive result. MacKie therefore broadly accepted Thom's conclusions and published new prehistories of Britain. In contrast a re-evaluation of Thom's fieldwork by Clive Ruggles argued that Thom's claims of high accuracy astronomy were not fully supported by the evidence. Nevertheless, Thom's legacy remains strong, Edwin C. Krupp wrote in 1979, "Almost singlehandedly he has established the standards for archaeo-astronomical fieldwork and interpretation, and his amazing results have stirred controversy during the last three decades." His influence endures and practice of statistical testing of data remains one of the methods of archaeoastronomy.